Before a participant begins mFOLFOX6 chemotherapy, they will have a central venous line inserted for the intravenous (in a vein) chemotherapy administration. This is called a "port" or vascular access device. Insertion of the port is a minor outpatient surgical procedure that is performed by a surgeon or interventional radiologist depending on where it is done. The doctor will arrange for the participant to have this procedure done before the participant begins.